THURSDAY, June 19, 2014 (HealthDay News) -- U.S. veterans of the Iraq and Afghanistan wars who suffered brain injuries are at a much higher risk for headaches, especially migraines, a new study finds.

Deployment-linked traumatic brain injury "is associated with a strong and highly significant increase in frequency and intensity of headache, the majority of which are migraine," concludes a team led by Dr. James Couch, of the University of Oklahoma Medical School in Oklahoma City.

Couch's team noted that traumatic brain injury is the "signature injury" for U.S. troops deployed in the conflicts in Iraq and Afghanistan, "occurring in 15 percent to 20 percent of deployed soldiers." They added that "combat zone deployment, by itself, is stressful. Both traumatic brain injury and stress are known to be associated with headache."

The new study included 53 veterans who had suffered a traumatic brain injury during deployment and a "control" group of 53 veterans without brain injuries. Couch's group reported that all of the veterans in the brain injury group said they experienced headaches, compared with about 76 percent of those in the control group.

The frequency and intensity of headaches were much higher in the brain injury group, the investigators found. Compared to the control group, the incidence of frequent headache (10 to 14 days a month) was 4.5 times higher and incidence of chronic headache (15 or more days a month) was three times higher in the brain injury group.

Migraines accounted for 89 percent of headaches among veterans in the brain injury group, compared with 40 percent of those in the control group.

The findings will be reported later this month at the annual meeting of the American Headache Society in Los Angeles. Findings presented at medical meetings are typically considered preliminary until published in a peer-reviewed journal.